In a mobile phone, a cabinet is fixed to a chassis to configure a device main body, and one or a plurality of constituent members configuring the cabinet are fastened to the chassis with a metal screw member (for example, see Patent Document 1).
In recent years, in order to reduce a mobile phone in size, it is conceived that a chassis is formed by using a magnesium alloy. According to the chassis made of a magnesium alloy, the chassis can be processed to have a complex shape and can be reduced in thickness. On the other hand, as a metal configuring the screw member, stainless steel (SUS) is conventionally used. According to the SUS screw member, the strength is increased.